The present invention relates to a new and improved construction of laser or laser arrangement containing a laser resonator possessing a laser rod and an electro-optical modulation device between two mirrors, the modulation device comprising a polarization element and a component containing an electro-optical crystal at the opposite faces or sides of which there are arranged electrodes.
Devices of this type are already known to the art wherein the optical surfaces thereof are provided with anti-reflection layers in order to maintain the reflection losses as small as possible. However, the anti-refection layers are associated with the drawback that they become damaged when exposed to the high load of the laser beam or radiation in the laser resonator, and they only can be applied with difficulty to hygroscopic electro optical crystals, especially KDP and KD.sub.2 P (potassium-dideuterium phosphate), and thus, possess only a short service life or longevity.